Whitney, Hassler; Tutte, W. T. Kempe chains and the four colour problem. (English) Zbl 0328.05107 Stud. Graph Theory, Part II, MAA Stud. Math. 12, 378-413 (1975). Page: −5 −4 −3 −2 −1 ±0 +1 +2 +3 +4 +5 Show Scanned Page Cited in 3 Documents MSC: 05C15 Coloring of graphs and hypergraphs 57M15 Relations of low-dimensional topology with graph theory PDF BibTeX XML